Keyboard electric musical instrument



M. MARTENOT KEYBOARD ELECTRIC MUSICAL INSTRUMENT July 31, 1951 3 Sheets-Sheet 1 Filed April 5, 1948.

bhlrbbb y 1951 M. MARTENOT 2,562,471

KEYBOARD ELECTRIC MUSICAL INSTRUMENT Filed April 5, 1948 5 Sheets-Sheet 2 July 31, 1951 M. MARTENOT KEYBOARD ELECTRIC MUSICAL INSTRUMENT 3 Sheets-Sheer,

Filed April 5. 1948 Patented July 31, 1951 UNITED" STATES. eATEN-r OFFICE;

KEYBOARD ELECTRIC MUSICAL INSTRUMENT,

MauriceMartenot,Neuillyesur- Seine, France.

Application April 1948; Serial N 0. 19,123 In France April14, 1947 This invention relates to improvements inkeyboard electric musical instruments, i. e. those in which the electric circuits generating 1 the various sound frequencies are controlled by keys on- Which the performer plays --as--he Would-do on" the flnger-keys'of a piano," for example;

There is already known forsuchinstrumentsa-movable keyboard deviceprovidingsound pitch variations independent of those obtained by means of the keys-and allowing, e. g-., short glissandi or vibratos correspondingtothe manner of playing of the'performer.

Sincethe shifting of thekeyboard varies the sound pitch, it is-essential that after each of such shiftings the'keyboard resumes its original position with a high accuracy, failing which the instrument may fall out of tune perceptibly enough to disturb the performance.

Moreover. in spite of the lightness of the materials used, the keyboard assembly, constitutesamass which-does not easily-follow the oscillations requiredby the hand which are sometimes ample and quick. Therefore the inertia of the mass must be compensatedby adevice providing a strong restraining actiorras-well as a powerfulv return or draw back-motion.

One of the improvements to which this invention relates makes it possible tomeet the above mentioned requirements; According to said improvement the movable keyboard is associated with means ensuring its returnor drawbackmotion-and guiding-it as well, and the drawback means which offer tothe keyboard motion a mechanical resistance increasinginterms of the departure on either side of the neutral position,

are sodesigned that the frequency of the keyboard free oscillations has a materially higher value than the vibratos oscillations commonly used during performance.

Another improvement accordingto the-invention and which may be applied separatelyorsimultaneously with the first one relates to the 10. Claims. (Cl. Sale-423) Nowin the monodic instruments of theeleo tronic type to which this invention is more-par ticularly-relative the' contacts operated by thekeys-should control circuits which are sensitive tothe slightest variations-ofresistance. It will he therefore understood that the quality'of' said contacts should be absolutely perfect. Thus, for"- example, in the instruments the contacts of which vary the inductance =or-the resistanceof oscillating circuits or of their associated circuits,

the-contacts operating by a mere pressure have been found inadequate.

According toone improvement which consti-n tutes one object oithe -invention the movable part of the contact which acts by friction slides along-a continuous surface dividedinto insulating and conducting-sectors so that. the circuit is: open 'or closed accord-ing to-the position of. the movable part along saidsurface, on which said-1- part may thus continually rest.

It will be easily understood by reading the fol-#- lowing description-with' reference to the'accompanying drawing givenasan illustration which; does not limitthe invention; how it may be-ern=- bodied-the features resulting from the drawing as well as-froin the-description pertaining,- oi

Inthecourse, to the scope-of said invention. drawing:

Fig.- 1 is a'diagrammatical elevation view of; one end of an improved movablekeyboard ac cording to the invention. The device is symmeta rica-l with respect to a'verticalplane such as indicated at YY.

Fig. 2 is an elevation view ofan intermediate part of the keyboard provided with a modifieddevice.

Fig. 3 is an end viewof a-keyboard showing another modification ofthe 1 suspension device" of said keyboard.

Fig. 4 is a sectional view of Fig. 3 taken along line IV--IV.

Fig. 5 is an endview of a keyboard provided with another modified suspension device.

Fig. 6 is a side view of one key of the keyboard with the associated movable contact.

Fig. 7 is a similar but enlarged view of one-of the stationary surfaces with which the movable:-

contact oo-operates- I Fig. 8 is a side view of said surface. Fig. 9 shows as aside view the pair of sta-- tionary surfaces and the co-operating movable contact.

' Fig. 1-0 is an underneath plan view of Fig. 9.

"Fig-'11 is a'view similar to Fig. 9 and showing an alternative embodiment of the contact.

Fig. 12 is a plan view of an embodiment of the invention according to Figs. 2, 3, 4 and 6, Figs. 2 and 6 being sections taken on the lines II-II and VI-VI, respectively, and Fig. 3 being an end view looking in the direction of the arrow F of Fig. 12.

In the embodiment shown in Fig. l keyboard frame A supporting a set of keys B is mounted on rollers C which move along incurved rollertracks D carried on a stationary base or support D1. If the keyboard is moved longitudinally (it could be moved transversely by orienting the rollers in the width direction) it will always tend to resume rigorously its original position. Moreover, due to the bending of roller-track D, the more considerable the departure on both sides of the neutral point is the greater the resistance will be.

To make the construction easier, the device may be inverted and the roller tracks may be integral with the movable frame while the rollers will be disposed on a stationary base. There will be provided on the keyboard as many devices of this type as will be necessary for its suitable seating and good operation. They will be conveniently added with one or more springs F and stops and H limiting the amplitude of the motion. The rollers may also be substituted by balls suitably mounted or by a pivoting on pin or hinge.

The drawback force exerted by gravity in the roller-tracks D and combined with the action of springs F should ensure a natural frequency of the keyboard higher than the usual vibratos frequencies.

Fig. 2 illustrates another drawback device. It

comprises a spring-leaf R. secured on one side to a point R1 of the movable keyboard A, on the other side to a steel wire R2 tightened between two coil-springs R3 secured on a stationary frame D1.

This device may be mechanically inverted, the spring-leaf being then integral with the stationary base and the wire and the coil-springs being secured on the movable keyboard. The strength of the springs should be determined with respect to the mass of the movable keyboard so as to ensure to said keyboard a natural frequency higher than the usual vibratos frequencies which can be manually realized by a musician.

This return and damping mechanism acting on the movable frame A may be associated with supporting devices for the frame, similar to those of Fig. l or of Fig. 3 and 4 hereunder described.

According to Figs. 3 and 4 two parts A1 and D2, one of which is secured on the movable keycarrying frame, the other one being secured on the stationary support, are interconnected by means of flexible strips I made of metal or of any other material. Point-ended metallic rods J are clamped between two cups, one of which at least J1 is adjustable to allow an accurate adjustment according to the length of strips C.

Conversely, it is possible to use rods the dished ends of which would be clamped between central point-screws.

A plurality of such devices may be disposed along the length of the keyboard suitably securing said keyboard while ensuring its maximum movableness. Alternatively Fig. 5 shows a device in which rods J are horizontal instead of being vertical. Said rods are interconnected in pairs by means of leaves K. In each pair the upper rod is clamped between adjustable cups J1 secured on the movable keyboard A while the lower rod is clamped between cups J2 supported on fixed support D1. This device might be further modified by securing leaves K at one end on the movable frame, for example, and by linking them at their other end on the stationary support as described above or conversely. In this case leaves K should, of course, be flexible enough.

Fig. 6 shows a general view of the contacting device associated with each key. Frame A of the keyboard seen in section carries a key B secured thereto by means of a spring-leaf B1 which ensures the drawback motion of the key and is secured on the frame by means of a screw B2. A rod B3 integral with the key controls through a wire E4 the motion of a light spring B5 secured on a small insulating bar A2. Near to the end of said spring a tube L, preferably made of noble metal engages the arms of two contacts L1, also made of noble metal, as soon as key B is depressed. The adjustment of the attack point of the contact is ensured either by twisting rod B3, or by turning it if it is screwed or merely keyed in the key.

Figs. 7 and 8 show one contact arm L1 enlarged.

twice. A steel wire L2 supports a metallic portion M the extension of which is embedded in a perfectly insulating plastic substance N. Conducting surface M and insulating surface N are adjacent in the same plane.

Fig. 9 shows the metal tube L, which constitutes the movable contact, in its rest position at I, where it engages the insulator and in its end position at 2, where it rests on the metal. will be understood that said tube clamped between both contact arms and sliding first on the insulating portion, soon engages the two metallic portions which are continually cleaned by the wiping action which ensures a perfect twin-contact. It will be also understood that such a device is absolutely noiseless and cannot get out of order, the tube being continually guided either by the insulating portion or by the metallic portion of each contact.

The invention comprises various other embodiments, e. g., by substituting for metallic leaf M a thin film of metal deposited by spraying or by electroplating or by shaping movable part L otherwise on by controlling it through any other device than that shown in Fig. 6 as an illustration. It is also possible to shape otherwise the metallic portion and to engage it on its edge instead of engaging it on its face, or to replace the fiat surfaces by two rods or tubes T, T one portion of which Tn would be insulating, the other portion Tm being conducting (Fig. 11).

Moreover it is to be understood that the described embodiments have been given merely as illustrations and that they could be modified, particularly by substitution of technical equivalents within the scope of the invention.

What I claim is:

1. In an electrical musical instrument, a sta-.

oscillating movement on either side of a middle. position, means between said frame and said support for permanently urging said frame to said middle position, said urging means and said,

frame forming together an oscillatory bodythe oscillation frequency of which is a function of the strength of said urging means and of the mass of the frame, said strength and mass being so correlated that the said frequency is higher than the frequency of the tremolos which may be manually obtained by a musician.

2. An electric musical instrument according to claim 1 in which said frame-supporting means comprise surfaces, bearing means resting on said surfaces and flexible leaves arranged between the frame and its stationary support.

3. An electric musical instrument according to claim 1 in which said frame-supporting means comprise surfaces, knife-edges resting on said surfaces and flexible leaves arranged between the frame and its stationary support.

4. An electric musical instrument according to claim 1 in which said urging means comprise at least one leaf-spring fixedly secured at one end to said frame, and tie-rods, said leaf spring being linked at its other end with said tie-rods.

5. An electric musical instrument according to claim 1 in which said urging means comprise at least one leaf-spring fixedly secured at one end to said frame, tie-rods linked with said leafspring at its other end, and coil-springs controlling said tie-rods.

6. An electric musical instrument according to claim 1 in which said electric contacts comprise a smooth surface constituted by at least one insulating area and one conducting area in the prolongation of the first one and a movable metallic cylinder moving along said surface, said movable member being mechanically connected to the corresponding key.

7. An electric musical instrument according to claim 1 in which said electric contacts comprise a smooth surface constituted by at least one insulating area and at least one conducting area in the prolongation of the first one, said areas being adjacent in the same plane, and a movable metallic cylinder moving along said surface, said cylinder being mechanically connected to the corresponding key.

8. In an electric musical instrument, a stationary support, a frame movably arranged above said support, a set of keys pivotally mounted on said frame, electric contacts on said frame each operatively connected to one of said keys for generating sounds of different frequencies, a set of vertical rods having sharp ends, said rods being inserted between points of said support and of said frame respectively for supporting said frame on said support while allowing the oscillating motion of said frame with respect to said support on either side of a middle position, and resilient means secured to the support and to the frame for permanently urging said frame to said middle position, said resilient means and said frame forming together an oscillating body the oscillation frequency of which is a function of the strength of said resilient means and of the mass of the frame, said strength and said mass being so correlated that the said frequency is higher than the frequency of the tremolos which may be manually obtained by a musician.

9. The combination of claim 8 comprising further on said frame and on said support adjust-' able cups receiving the sharp ends of said vertical rods.

10. The combination of claim 8 comprising further on said frame and on said support adjustable cups receiving the sharp ends of said vertical rods, and vertical flexible leaves secured to said support and to said frame in order to maintain said rods in close engagement with said cups.

MAURICE MARTENO'I.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,053,551 Avisus Feb. 18, 1913 1,448,058 Eis Mar. 13, 1923 1,550,868 Beyer Aug. 25, 1925 1,586,258 Mills May 25, 1926 

